Some endovascular procedures require stent grafts to have temporary access ports or fenestrations. Various fenestrations have been developed that are openable or closeable and can therefore be described as valved fenestrations. Difficulties with existing valved fenestrations within stent grafts include the space they require and limitations on where they can be placed with respect to expandable stents and bifurcations for instance. Difficulties can arise in design of closing mechanisms for valved fenestrations as well.
Throughout this specification, when discussing the application of this invention to the aorta or other blood vessels, the term “distal” with respect to a prosthesis is intended to refer to a location that is, or a portion of the prosthesis that when implanted is, further downstream with respect to blood flow; the term “distally” means in the direction of blood flow or further downstream. The term “proximal” is intended to refer to a location that is, or a portion of the prosthesis that when implanted is, further upstream with respect to blood flow; the term “proximally” means in the direction opposite to the direction of blood flow or further upstream.